I want to install an hour meter in the engine room and I need a power supply that only runs when the engine runs. Can I attach the positive terminal to one of the two smaller terminals on the back of the alternator marked D and W. If so, which one. Is one of these terminals for the tachometer and can I use it? Or should I simply tie into one of the wires connecting the temperature or oil sensors to the guages at the helm station? Can I attach the negative terminal to a convenient point on the engine block? Thanks in advance for the advice.
Electric Gurus
- Thread starter Peter Milne
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Hourmeters are generally powered chronographs that measure time (hours) when they are powered-up and running. Whenever they are not powered up and running, they remain frozen in time sort of speak. There are some hourmeters that are always powered up via an internal button battery. They will continually display a digital readout on an LCD display. They work on sensing vibration. Whenever the engine is on, they are counting up hours. The good thing about these hourmeters are that they are cheap, easy to mount, requires no wires to hookup and are disposable when the need arises. The type I believe you have is the kind that requires a power source. Generally 12 volt system power. The grounding terminal should be run through a switchable source such as an ignition ground or oil switch (if it is normally open type) which generally most are. Most of the time, the altenator is connected to the oil pressure switch which serves as a switch to sink altenator Field or Relay signals. This keeps the altenator 'turned off' when the engine is being cranked over. Otherwise the altenator would saturate its stator windings and lock up the starter motor from freely turning the engine over. So my guess it to look over the hourmeter or refer to the data sheet and connect a power source to it. Run the other wire (ground lead) to a place in the system that can switch ground to it (and thus 'turn on' & run the hourmeter). A good place would be the ignition switch. Most have a terminal that is dedicated to sinking current when the key is in the run position. This of course isn't as precise as having the meter sunk through an engine run device such as the oil pressure switch, because only then will you be assured that the engine hours are being logged accurately. Good luck Tom
Hourmeters are generally powered chronographs that measure time (hours) when they are powered-up and running. Whenever they are not powered up and running, they remain frozen in time sort of speak. There are some hourmeters that are always powered up via an internal button battery. They will continually display a digital readout on an LCD display. They work on sensing vibration. Whenever the engine is on, they are counting up hours. The good thing about these hourmeters are that they are cheap, easy to mount, requires no wires to hookup and are disposable when the need arises. The type I believe you have is the kind that requires a power source. Generally 12 volt system power. The grounding terminal should be run through a switchable source such as an ignition ground or oil switch (if it is normally open type) which generally most are. Most of the time, the altenator is connected to the oil pressure switch which serves as a switch to sink altenator Field or Relay signals. This keeps the altenator 'turned off' when the engine is being cranked over. Otherwise the altenator would saturate its stator windings and lock up the starter motor from freely turning the engine over. So my guess it to look over the hourmeter or refer to the data sheet and connect a power source to it. Run the other wire (ground lead) to a place in the system that can switch ground to it (and thus 'turn on' & run the hourmeter). A good place would be the ignition switch. Most have a terminal that is dedicated to sinking current when the key is in the run position. This of course isn't as precise as having the meter sunk through an engine run device such as the oil pressure switch, because only then will you be assured that the engine hours are being logged accurately. Good luck Tom
Engine key
Just tie it in off the key to turn on the engine. Whenever the key is on, the engine should be running and you'll capture the run hours. Find a 12v source off the key and a convenient DC ground source for the other side and you'll be in business.
Just tie it in off the key to turn on the engine. Whenever the key is on, the engine should be running and you'll capture the run hours. Find a 12v source off the key and a convenient DC ground source for the other side and you'll be in business.
Back of the switch
On the back side of your ign. switch there should be a terminal marked "I" , or a terminal marked "A", or possibly both. The I stands for ignition and the A for accessory. Both of these should be hot when the switch is on. Just tie on to one of these, go to the + side of the hour meter. - side of the meter goes to a good ground, and your good to go.
On the back side of your ign. switch there should be a terminal marked "I" , or a terminal marked "A", or possibly both. The I stands for ignition and the A for accessory. Both of these should be hot when the switch is on. Just tie on to one of these, go to the + side of the hour meter. - side of the meter goes to a good ground, and your good to go.
Misc wires in the harness.
Peter: Check out your wire harness in the engine compartment or at the pedestal. There are usually wires that are energized by the ignition key. You should be able to hook a volt meter to these wires and have someone turn the ignition key on/off to determine which ones run off the key. We did this on our '94 HV'36 and it was easy once we found the correct wire. You may also want to look in your Yanmar manual to help you locate the correct wire.
Peter: Check out your wire harness in the engine compartment or at the pedestal. There are usually wires that are energized by the ignition key. You should be able to hook a volt meter to these wires and have someone turn the ignition key on/off to determine which ones run off the key. We did this on our '94 HV'36 and it was easy once we found the correct wire. You may also want to look in your Yanmar manual to help you locate the correct wire.
Dont hook it up to the oil pressure sensor
because they are normally closed when there is no pressure - hence the buzzer when you turn the key on. When the engine is cranked, the pressure sensor opens - thus the alarm goes off. It would seem the ignition switch would be a good spot - do you ever break the cardinal sin of running the diesel with the key off? If you do, then the meter wont log correctly cause it will not get the +12V it needs. Any ground position will do cause it is just a simple guage that is not sensitive to ground location.
because they are normally closed when there is no pressure - hence the buzzer when you turn the key on. When the engine is cranked, the pressure sensor opens - thus the alarm goes off. It would seem the ignition switch would be a good spot - do you ever break the cardinal sin of running the diesel with the key off? If you do, then the meter wont log correctly cause it will not get the +12V it needs. Any ground position will do cause it is just a simple guage that is not sensitive to ground location.
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